Two-stroke engine



v Jan. 4, 1944. E, cLAvEAU 2.338.406

TWO-STROKE ENGINE Filed NOV. 19, 1941 7 Sheets-Sheet 5 1 the height of the Thus'the movable lobturaidn'g ring acts in 'co-"f" Patented'Jam 4,- 1944 f Emile Claveau, Paris, Pro

- l Application Novemberl A A'type of two-stroke enginey the admission under pressure of freshgases and the exhaust of burnt gases take place by means of ports which gine'pistonl successivelyl uncovers and covers the. said ports during a partjof its up.-v and down-1 lie one above another. The enstrokes in the neighbourhood of its .lower dead'- f.

centre. The drawback a portion of tli'"fresh gases passes through the exhaust ports.

of engines ,O f this kind is f'. that the admission and exhaust ports remain 'si-` multaneouslyI during a short time so that ctly out vThis invention relates to atwo-stroke engine inrv which this drawback is avoided. This engine is chiefly characterized by the fact that a movable obturating ring which is broad enoughvfor covering the exhaust ports -andwhlch is in con-y tact with the inner face of the .cylinder is brought by the piston in front of the exhaust the admission period of fresh gases, rwhile ports during this obturating ring is drawn away by the piston from its position inA front lof the exhaust ports during the exhaust'period. For this purpose, the piston is, for instance, provided with an upper extension comprising' ar groove,- and' with openings which connect the inside of the cylinder. during the A Tigllres 4 ".cylinder and of .thepistcn of the engine of' a l second form thereof, in positions corresponding Figures 12 to 15 .tothose of Figures 2 to; .Figuresii to 19 are Vdia'grammatical views fourth form t0 those @Figure tional view through a modined form of slide valve,', f'

. .In the form of -4 ii). f,;;; isknown in which s u 11 are diagrannlatical views' or me eylinderand of- 6, respectively;

of and of the piston of the 'engine cfa thereof, in positions corresponding of Figures 2 to 6, respectively;

the cylinder Figure lill is .a fragmentary longitudinal sectional view Athrough anothery modifiedjform of slidevalve.V 1 A execution in which it is shown in the drawings the engine comprises a cylinder I inside of which 4a. piston! can move, which piston is connected by a connecting 'rod vI and a crank l 'to the engine shaft i.

down-stroke of the piston, successively with the v exhaust ports and then with 'the admission ports.

The obturating' ringl which is continuously main- 'tained applied against the innerv wall of the cy1.

inder byits elasticity is alternately displaced, in l a reciprocating motion. with .intermediate intervals vof rest, by the upper edge and then bythe f .1'. lower edge andthe height of-which is larger than of the piston groove in which the said ringis set said ring.

'v operation with the' piston as -a slide.' valve byv means of whichvthe inside of the cylinder is 'suc'- eessively connected with the exhaust ports vand then with the admission ports, the exhaust ports llueing closedduring the period of admission.'

'Several embodiments of the invention are -Y- shown by way of non limitative examples in the appended drawings." In these drawings:

Figure` l is a diagrammaticai axial sectional view of the engine which is supposed to be a single-cylinder engine.

Figures 2 to 6 are diagrammatlcal views of the cylinder and of the piston of the engine on a larger scale and in different positions of the piston. v v

Figure 'Z is a cross-sectional view of the piston and ofthe cylinder of the portlevelinthecase ofrigure2.

engine at the exhaust Finally, l2 vare packing lrings providedin- -the'ff v When the piston 2 is at its lower "dead'fcentref' I' sion and exhaust pipings cannot l any way. y

The piston-2 comprises a-recessed bottom-2' which forms a kind of head the walls of which are provided withone or more openings, Ba (Figures 2 and 7). It-compris'es furthermore, on

its external face, an slidablering valve 8 is located, the heightcf the said ring valve beingless than the height of the 4The said ring'is split and L @is the 'latter' is closed the ignition member'(notr showniissecured.

piston 2.

' Theoperationis as follows:

(Figure 2) the admission ports I0 arev uncovered f while the exhaust ports l are covered by the slide ringvalve 8.

The admission of the cylinder takes one of the usual means gines. are covered by the slide ring valve l, the` admis- The Pilbon its 1D-stroke.

are diagrammatical views ofthe the pistons: the 'engine .of ai .third form thereof. in positions corresponding 2 0 is a fragmentary longitudinal secr l annular recess 1 in which a has'v a certainelas- Y ticity-'so that it always remains applied against the inner wall ofthe cylinder. q -9' and Ill are the exhaustand n ..respectively,-bored in the cylinder. i.v v.

f mritsupper part ordinary threaded plug il screwed' into o. tapped hole and to which the explosive mixture into v place at this moment through 4 used for twoestroke enf Owing to the fact that the exhaust ports communicate in slide ring valve 8.

When it has effected a stroke which is equal to the height of the admission ports Iii it has the explosivev mixture continuing.

When the piston 2 is about to reach its upper dead centre (Figure 4) the explosion takes place and the piston begins its down-stroke. Shortly afterthe beginning of the latter, the upper edge of the recess 'l of the piston (position shown by dotted lines) draws along in a downward direction the slide ring valve 8 which had remainedl during 'this time pressed against the cylinder wall duefto its elasticityand to the pressure of the j cylinder gases on its internal face.

The down-stroke or expansion stroke of the l piston goes on until the exhaust ports 8 are uncovered (Figure 5); then the burnt gases pass rapidly through the openings 8 of the piston and escapealmost instantaneously through the said exhaust ports 8. Then, these exhaust ports' are very rapidly covered by the slide ring valve 8 (Figure 6) and the admission ports I0 are about to be uncovered by the piston 2 and will be completely uncovered when the piston reaches its lower dead centre (Figure 2). the cylinder through the said admission ports I0 and through theopenings 8 of the piston under the action oi'y any known admission means used in two-stroke engines, this admission being promoted by the vacuum obtained in the cylinder by the perfect obturation of the exhaust ports by the And so on.

In the form of execution shown in Figures 8 to 11 the ring 8 has a height which is substantially equal to the distance between an admission and an exhaust port. y

In the form of execution shown in Figures 12 to 15 the ring 8 is-high enough to project beyond the recess 1. collar 8a with which its lower part is provided. With this arrangement it is possible to ensure a lsubstantial overlapping of the exhaust ports 8 by the slide ring valve 8.

Fresh gases enter It is drawn along by an innerA In the case of Figures 16 to 19 the slide ring valve is provided with two inner drawing collars 8a and 8b.

Operating conditions in the case of the threev above mentioned embodiments are the same as those shown in Figures 1 to '7.

Figures 20 and 21 show an elevational view with apartial sectional view of a portion of a slide valve 8 made of thin metal and provided with grooves such as 8c in which a graphitic paste 8d is placed which ensures a good lubrication of the slide valve ring, A i

If desired, any shock absorber such as springs. thin corrugated blades, gas cushion with a vent vor the like can be inserted between the ring 8 and the upper and lower edges of the recess 1.

I claim:

1. A two stroke engine comprising a cylinder, a piston, an exhaust port and an admission port located in the inner surface of the cylinder, these ports being successively covered and uncovered by the piston, a ring sliding in the cylinder and cooperating with the said exhaust port, said ring being in frictional contact with the cylinder to such degree as to hold the ring against sliding to enable the piston to have a sliding movement relatively thereto and independently thereof, a head protruding from the upper part of the piston and formed with an annular outer vrecess provided with openings facing the exhaust and admission ports and with two transverse surfaces capable of engaging the sliding ring to move the ring to a limited extent with the piston and 1ocated at such a distance apart from each other that when the piston uncovers the admission port the exhaust port is covered by the sliding ring and that, after the piston has covered the admission port, it covers the exhaust port and carries away with it the sliding ring.

2. A two stroke ,engine comprising a cylinder, a piston, an exhaust port for the exhaustion of burnt gases out of the cylinder, and an admission port for the admission of a fresh explosive gaseous charge into the cylinder, these. ports cooperating with the piston for the exhaustion of the burnt gases and for the admission of the fresh explosive charge, and an elastic sliding ring expand- 'ing into contact with the inner surface of the cylinder to such degree as to hold the ring against sliding to enable the ring to have a sliding movement relatively thereto and independently thereof, said ring being large enough to cover the exhaust port and means carried by the piston to move the said ring through abutment therewith in front of the admission portand cover it when the inlet port is uncovered.

3. A two stroke engine comprising a cylinder laterally provided with an exhaust port and an admission port, an explosion chamber, a piston provided with an outer annular recess and cooperating with -the said exhaust andl admission ports for the exhaustion and the admission of the motive gases of the engine. the said annular recess matching with both the exhaust and admissionv ports when the piston approaches the end of its outer stroke, conduits leading through the piston from the inside of the said annular recess to the cylinder explosion chamber, an expending ring in frictional contact with the inner wall of the cylinder to such degree as to hold the ring against sliding to enablethe ring to have a sliding movement relatively thereto and independently thereof, said ring being broad enough to close the outlet port, an upper abutment carried by the annular recess and capable of engaging with the slidingring and of driving it to a position for which it covers the exhaust port before the piston uncovers the admission port, a lower abutment carriedv by the annular recess and capable of engaging with the sliding ring after the piston has covered the admission port and driving the said annular ring together with the piston. t

4. A two stroke engine comprising an exhaust and an admission port, a piston cooperating with 

